Borofutus dhakanus

Borofutus dhakanus Hosen & Zhu L. Yang, in Hosen et al., Fungal Diversity 58: 219 (2012)

Etymology: dhakanus refers to the name of type locality (Dhaka).

Basidiomata small to medium-sized. Pileus 30–65 mm, convex when young, becoming plane with age, covered with light brown (6D8) to cocoa brown (6F7), grayish brown (6F3–4) to dark grayish brown (6F6–7) squamules, which become grayish black (6F1) at maturity; center sometimes umbilicate, depressed, not glabrous, becoming rimose with age, dry, somewhat slightly tacky when wet, margin occasionally uplifted. Hymenophore tubular, subdecurrent, pallid to creamy to yellowish (4A1–2), turning pale reddish to pale reddish purple on exposure to air for long time when young, becoming light brown (6D6–8) to golden brown (5D7–8) at maturity; pores 5–11 mm depth, 4–10 mm length and 2–6 mm wide, sometimes double-pored, mostly hexagonal, relatively broader towards the centre then gradually narrower towards the margin, with reddish powdery mass inside the tubes when aged. Stipe 25–40×6–12 mm, central, cylindrical, narrowly tapering upwards, occasionally slightly swollen to the base, mostly curved, covered with purplish to grayish to cocoa brown squamules; apex glabrous, whitish to creamy to yellowish; upper half ribbed by the subdecurrent lines of the hymenophore; basal mycelium whitish. Context 5–15 mm thick in the center of the pileus, solid, yellowish to creamy, usually unchanging when bruised but in some specimens turn pale reddish to pale reddish purple when exposed to air for long time. Taste unknown and Odor mild.

Basidiospores [320/16/16] (10) 11–13 (14) × (4.5) 5–6 (6.5) μm, [Q= (1.97)2.08–2.52(2.92), Q_m= 2.29 ± 0.16], boletoid to somewhat amygdaliform, slightly thick-walled (0.7 μm), brown-violet to purple to purplish red (11C6–8, 11D6–8) in H₂O, purplish violet (11E5–8, 11F5–8) in 5 % KOH; surface finely verrucose under light microscope (LM), but ornamented with irregular to regular, conspicuous shallow pits under SEM. Basidia (20) 31–33(39) × (7) 9–10(12) μm, narrowly clavate to clavate, hyaline to pale yellowish in H2O and glycerin, thinwalled, tetrasporic, occasionally 2- or 3-spored, bearing relatively long sterigmata (5.0–8.5 μm long). Hymenophoral trama 110–170 μm wide, bilateral; hyphae cylindrical, hyaline, 7– 20 μm wide. Cheilocystidia abundant, (45)70–80(100) × 7– 14 μm, narrowly lageniform to lageniform to broadly lageniform, sometimes narrowly utriform to mucronate, rostrate, slightly thick-walled (0.6–1.2 μm thick), with an attenuate appendage, sometimes with a secondary septum; inner surface often with brown to greenish brown pigmented ornamentations. Pleurocystidia 85–105×12–20 μm, thin-walled to slightly thick-walled (up to 0.5 μm thick), scattered, narrowly lageniform to broadly lageniform with an appendage-like apex, without encrustation. Pileipellis a trichoderm when young, becoming a subcutis at maturity, composed of 4–5 long cylindrical cells; terminal cells 25–60(−105)×5–10(−13) μm, with brown to chocolate brown vacuolar pigments. Stipe trama composed of vertically arranged hyphae. Stipitipellis a sterile hymenium-like structure, composed of subclavate to clavate to fusiform cells with projecting cystidia (40–50×8–15 μm) with yellowish brown to pale brown vacuolar pigmentation. Clamp connections absent in all tissues.

Habit and habitat: Mostly solitary or often in small groups, and usually found growing in clayey soil rich in Fe in pure stands of Shorea robusta.

Known distribution: Currently known only from Bhawal National Park, Gazipur, Dhaka division, Bangladesh at 20 m elevation.

Index Fungorum number: IF800167

Figure 1. Phylogenetic tree generated from nrLSU dataset of 55 sequences in the Boletales using ML method. Posterior probabilities from Bayesian inference (BI) (>0.94) are indicated as thick branches and bootstrap values derived from ML and MP analyses (BS> 50 %) are shown above or beneath the branches at nodes. Parsimony analysis resulted in two most parsimonious trees of 1,726 steps, with Consistency Index (CI) =0.314, Retention Index (RI) =0.506 and Rescaled Consistency Index (RC)= 0.182. GenBank accession number for each sequence is provided behind the species name

Figure 2. Phylogenetic tree generated from the combined 5.8S, nrLSU, tef1-α, rpb1 and rpb2 dataset using ML method. Posterior probabilities from BI (>0.98) are indicated as thick branches, and bootstrap values derived from ML and MP analyses (BS>50 %) are shown above or beneath the branches at nodes. Parsimony analysis resulted in two most parsimonious trees of 7,140 steps, with Consistency Index (CI) =0.445, Retention Index (RI) =0.488 and Rescaled Consistency Index (RC) =0.239. Borofutus dhakanus is highlighted in boldface. Herbarium voucher or isolate number is provided behind the species name